Patent GB-1357615-A (GB)
Title: Method of and apparatus for composing pages of printed material
IPC: H04N1/387
Filed: 1971-04-19
Abstract: 1357615 Cathode-ray tube displays; photocomposing HARRIS-INTERTYPE CORP 19 April 1971 [20 Feb 1970] 21113/71 Headings H4F and H4T [Also in Division G4] In an arrangement for composing a page of text material (copy) to be printed a character memory stores a font of characters at addressable locations, respective terminal means store in a computer memory the addresses of characters to be printed and data indicative of the page and the location on the page at which an item is to appear, cathode-ray display tube means displays page areas and a photo-typesetter controlled by the computer records the text material on a film. Fig. 1, shows a flow diagram indicating the composing of a newspaper page and includes a computer terminal 28 having justifying means and display means to enable editing functions to be performed, scanning means 18 and 27 (see also Fig. 2) for scanning art work to provide data signals for storage and a terminal 34 (see also Figs. 4 and 5) associated with the layout department 20 and including cathode-ray tube display means showing page areas including "blocked off" portions already allocated by the display department together with identification of the text material to appear in such areas. The scanners 18 and 27 may take the form shown in Fig. 2, which includes a drum 50 to which the copy to be scanned is clamped by means 51 the drum being rotated by a synchronous motor 52 and providing, via a mechanically driven pulse generator 54, one pulse on line 55 for a predetermined increment of rotation and a pulse at the start or end of each revolution on line 74. The copy is scanned by a scanning head 58 including a mirror 80 which directs laser light onto the copy and a photodiode 60 which receives reflected light the head being indexed axially by one increment (preferably variable to allow scans of between 180 and 720 lines per inch) for each drum revolution via a lead screw 62 rotated by a stepping motor 64. In operation, at the start of each scan, the copy is assumed to be white (background) and a sum length counter 86 commences to count the pulses on line 55 until a black portion is scanned when in response to an output from level detector 83 (responsive to an output from the photodiode 60), the count is transferred via gate 87 to a Huffman encoder 96 and the counter is reset. As the scan continues counter 86 again counts the pulses on line 55 until a white portion is detected at which the count is again transferred to encoder 96 and this operation continues until the drum has made a complete revolution at which time a stop scan register and comparator 105 in response to correspondence between an end of line (EOL) code in a register 104 and the count in address counter 72 (which counts the pulses on line 55 and is reset by pulses on line 74) supplies a stop scan signal which via AND gate 109, OR gate 90 and AND gate 87 transfers the count in counter 87 to encoder 96 unless it relates to white background, which it is not necessary to encode, such transfer being prevented by a NOT white input to AND gate 109. The stop scan signal is also supplied, with a delay, to gate 106 to gate the EOL code to encoder 96 and also sets a multivibrator 110 to stop pulses to counter 86 and to prevent transfer of the count to the encoder 96. The pulse on line 74 which resets address counter 72 occurs as the clamp 51 starts to move past the scanning head 58 and when it clears the head and a new scan is about to start scan start circuit 114 is activated by the count in counter 72 and resets multivibrator 110 so that the first number transferred from counter 86 to the encoder 96 is the run-length number for the background at the start of the next scan. In this manner a runlength code which assumes a white beginning and thereafter black and white alternatively and includes an end of line (EOL) code to indicate the start of each new scan is stored in a core memory 98 acting as a buffer for a magnetic tape recorder 120 to which information identifying the copy and specifying the scanning resolution (the distance between successive scans), the column length and the column width. When the copy being scanned has a continuous tone (e.g. photographs) instead of black-andwhite (half-tone) the output for the scanning head 58 is supplied to an A/D converter 150 the digital output of which (indicative of the level of the signal from head 58) is converted to a half-tone screen dot code by decoder 151 each of which may cover a range of levels in the output of A/D converter 150 or each change in the latter may represent a new screen size. When continuous tone operation is required a select bi-stable control circuit 158 is set, to remove conditioning inputs to AND gates 88, 88a, to condition AND gate 156 and to condition AND gate 158a to pass a signal from a change detector 153, which is produced when there is a change in the output of screen size decoder 151, via gates 89, 91 and 90 to transfer, via gate 87, the run-length member in counter 86 to the encoder 96 and via gate 155, a delay device and gates 55a and 154 to gate the new screen dot code to encoder 96 when gate 155 is conditioned by the reset output of scan control multivibrator 110. Instead of delaying the activation of gate 154 the numbers in counter 86 and decoder 151 may be simultaneously gated to buffer stores in encoder 96 which are read in sequence so that the number in counter 86 is read first into core memory 98 followed by the number representing the new screen dot, the number from counter 86 representing the length of the scan segment for the preceding screen dot. When colour reproduction is required the scanning light reflected from the copy may be directed along separate paths each containing an appropriate colour filter and to avoid Moire patterns the computer may be utilized to produce angularly displaced dot patterns for the different colours. Fig. 4, shows the layout terminal 34 (Fig. 1) including a cathode-ray tube 160 on which page layout information stored in the computer is displayed an operator then assigning sections to particular items by means of adjustable X, Y co-ordinate markers 162, 163 the selected coordinates defining the various sections being automatically generated as the markers are adjusted and fed to the computer in addition to being displayed on devices 168 on each marker. In addition a keyboard 169 is employed to instruct the computer to draw lines in various directions with respect to particular co-ordinate positions. An alphanumeric keyboard 161 is employed to display heading information and additional display tubes 187, 188, 189 are provided to produce a display of the facing page, the backside of the page being worked on and a full page display of the page being worked on. A spot type cursor produced by the tube beam is moved by joy-stick control means 200 and on command, the co-ordinates of the spot may be entered into the computer. Fig. 5, shows the manner in which digital signals representative of the position of the X, Y co-ordinates markers 162, 163 are produced (Group G4), identical circuits 175, 175<SP>1</SP> being employed for the respective markers. As shown, movement of the X-co-ordinate marker 162 varies the position of a tap 170 on a potentiometer 172 to respective ends of which a voltage is supplied derived via D/A converters 182 fed with outputs from registers 180 in which numbers indicative of the left and right hand X- co-ordinate values are set. The voltage at the tap position is then fed via A/D converter 178 to an interface 179 and is also fed to the display devices 168 on the markers. When a portion of a page is displayed in magnified form on the display tube 160 the numbers set in registers 180 are such that the absolute co-ordinates are generated and fed to the computer. When a magnified portion of a page is being worked on the operator sets the right and left hand X-co-ordinates values in registers 190, 191 and by subtracting these values from one another and dividing the voltage value across potentiometer 172 representative of the full page width in circuit 193 a scale factor is produced and employed via multiplier 195 to cause the display of the selected portion in magnified form. The photo-typesetter employed to record the data on film may be of known type and the elements of a typical photo-typesetter are described with reference to Fig. 6 (not shown).